Corrugation-forming machines

ABSTRACT

A corrugation-forming machine includes two rotatable die rolls formed with intermeshing teeth between which material to be corrugated is passed. The teeth have sharp corners to produce corresponding sharp corners on the corrugated material. During operation the die rolls are oscillated so that their relative angular velocity varies to accommodate the different velocities that would otherwise arise between the tips and the roots of the teeth.

United States Patent [1 1 Couper et al.

[ Aug. 20, 1974 CORRUGATION-FORMING MACHINES [75] Inventors: Neale Sansome Couper, Conventry; Norman Philip Deane, Rugby, both of England [73] Assignee: Covrad Limited, Warwickshire,

England [22] Filed: Apr. 23, 1973 [21,] Appl. No.: 353,510

[30] Foreign Application Priority Data May 16, l972 Great Britain 22853/72 [52] US. Cl. 72/196, 72/443 [51] Int. Cl B2ld 13/04 [58] Field of Search 72/195, 196, 443; 425/336 [56] References Cited UNITED STATES PATENTS 448,073 3/1891 Price 72/196 2,022,082 ll/l935 Fisher et al. 72/195 3,367,l6l 2/l968 Avakian 72/l96 Primary ExaminerLowell A. Larson Attorney, Agent, or FirmMawhinney & Mawhinney 5 7 ABSTRACT A corrugation-forming machine includes two rotatable die rolls formed with intermeshing teeth between which material to be corrugated is passed. The teeth have sharp corners to produce corresponding sharp corners on the corrugated material. During operation the die rolls are oscillated so that their relative angular velocity varies to accommodate the different velocities that would otherwise arise between the tips and the roots of the teeth.

13 Claims, 7 Drawing Figures PAIENIEU AUBZOIUH SHEET 3 OF 3 1 CORRUGATION-FORMING MACHINES This invention relates to corrugation-forming machines of the kind in which strip, sheet, wire or the like material is formed into corrugations by being passed between two rotating die' rolls having intermeshing teeth, the corrugations being formed by the tips of the teeth on one die roll pressing the material against the roots of the teeth on the other die roll.

According to the invention a corrugation-forming machine includestwo rotatable die rolls formed with intermeshing teeth between which the material to be corrugated is passed, drive means for rotating said die rolls, and oscillating means arranged to cause the relative angular velocity of said die rolls to change during their rotation so that the angular velocity of one die roll is less than or greater than its mean angular velocity when the radius of the point of its teeth instantaneously in engagement with the teeth of the other roll is greater than or less than respectively the pitch circle radius of said one die roll.

Conveniently the oscillating means is arranged to oscillate both die rolls about their respective axes of rotation in opposite phase.

The oscillating means may be arranged to increase the angular velocity of one roll relative to the other when a tooth root of said one roll is engaged with a tip of said other roll and decrease the angular velocity of said one roll relative to the other when a tip of said one roll is engaged with a root of said other roll.

The die rolls may be mounted in bearings to rotate about fixed axes of rotation, both die rolls being connected through shaft means to meshing gears, at least one of said die rolls being connected to the corresponding meshing gear through universal joints, a first of said meshing gears being mounted to rotate about a fixed axis, and means to cause the second said meshing gear to roll back and forth around part of said first meshing gear when said die rolls are driven.

Alternatively the machine may include a pair of shafts driven at constant angular velocity, said shafts being connected to the respective die rolls to drive them, and the drive from at least one of said shafts to the corresponding die roll including a pair of Hookes joints so arranged as to produce sinusoidal variations in the angular velocity of the die roll driven thereby. Embodiments of the invention are described, by way of example only, with reference to the drawings, which are of a diagrammatic nature and in which:

FIG. 1 is an end elevation of part of two die rolls,

FIG. 2 is a perspective view of one embodiment of the invention,

FIG. 3 is an elevation of another embodiment of the invention,

FIG. 4 is a view, on a larger scale than FIG. 1, of part of a die roll, showing louvre-cutting surfaces,

FIG. 5 is a view on the arrow V in FIG. 4,

FIG. 6 is a side elevation of a die roll, with a portion enlarged to show louvre-cutting surfaces, and

FIG. 7 is a view of part of a die roll showing an alternative form of tooth.

Referring to FIG. 1 of the drawings, two identical die rolls 10, 11 have shafts mounted in bearings (not shown) to rotate about their respective axes 12, 13. The die rolls 10, 11 have equal numbers of identical, straight, intermeshing teeth 14 arranged parallel to the roll axes 12, 13.

The die rolls 10, 11 are used to form corrugations in a strip of aluminum foil 15 which is fed into the nip of the die rolls 10, 11 from the right-hand side as shown in FIG. 1 and which emerges at the left-hand side of the nip in corrugated form, and the problem is to form corrugations which have regularly-spaced sharp corners 16A between tips 16 and flanks 17.

Tips 18 of the teeth 14 may be formed as arcs of circles whose centres are the respective axes 12, 13. Similarly roots 19 of the teeth 14 may be formed as arcs struck about the respective axes 12, 13. The teeth are formed with sharp corners 18A (i.e. corners of small radius relative to the tooth height, for example of the order of two thousandths of an inch radius) between the tips 18 and flanks 20, and also with similar sharp corners 19A between the roots 19 and the flanks 20. The rolls 10, 11 may be spring-loaded towards one another, but they may be held at a fixed pre-determined spacing, so that the closure between the point of engagement of a tip 18 and the co-operating root 19 is substantially equal to the thickness of the strip 15, the arrangement adopted depending on the stiffness of the strip 15, and the shape of the flanks 17 required. The flanks 17 may be formed with louvres in known manner, by the provision of louvre-cutting teeth on the flanks 20 of the teeth 14, as will be described below. Although the flanks 20 have been shown as plane, they can be formed as arcs of circles to avoid tooth interference.

It has been found that if the die rolls have involute teeth, and one die roll is driven by drive means and the other is driven through interengagement of the teeth of the die rolls, corrugations are formed of which the tips. and roots are of inconsistent and indeterminate length. In addition, scuffing of the foil strip takes place and wear of the die roll teeth is increased. However, we

have found that by means of the present invention, corrugated strip having sharp corners may be accurately and consistently formed by providing teeth on the die rolls having sharp corners between the flanks and the tips and between the flanks and the root portions, and by cyclically varying the relative angular velocity of the die rolls in a manner to be described.

In accordance with the invention, the relative angular velocity of the rolls 10, 11 is caused to oscillate at a frequency according to the number of teeth.

At any instant one die roll is moved at an angular velocity relative to that of the other roll, such that, for example when a root 19 of one die roll is in engagement with a tip 18 of the other die roll, said one die roll rotates relatively faster than the other die roll. The actual relative angular velocities at this instant will be in the ratio of the root radius to the tip radius of the teeth 14.

In practice this change in relative angular velocity is achieved by imposing a smooth curve oscillation'on the angular velocity at which one or both rolls 10, 11 are driven. The instantaneous surface speeds of the interacting points of the teeth 14 will'thus be substantially identical, so that no slipping occurs. Ideally, in producing corrugations of the type shown in FIG. 1, the rolls 10, 11 would run at fixed, but different, angular velocities for a circumferential distance equal to the width of one tip 18, and then change at the comers of the tips and along the flanks 17 of the teeth to their appropriate other fixed angular velocities for the width of the next tooth tip. Such sharp changes of angular velocity are in general not practicable, but a considerable improvement over constant angular velocity drive can be achieved by imparting to one or both of the die rolls 10,

11, a substantially sinusoidal oscillation of appropriate- 18 of a tooth of one roll is in engagement with the root' 19 of the tooth of the other roll, then WR wr, Where W angular velocity of tip 18 R radius of tip 18 w angular velocity of root 19 r radius of root 19 With the mechanism according to the invention, there is an instantaneous point or line of contact between the teeth of the die rolls and the strip (or, strictly, two points or lines spaced apart by the thickness of the strip), and the locus of this point or line contact moves continuously along the foil in the same direction.

Thus the relative angular velocity between the die rolls will vary between zero, when the instantaneous point of engagement is at the same radial distance from the axes of rotation of both die rolls i.e. when the point of engagement lies on the teeth flanks at the pitch circle radius of both rolls; and a maximum when the instantaneous point of engagement is at a maximum radial distance from one of the rolls and a minimum radial distance from the other of the rolls, i.e. when the point of engagement is on the tooth tip of one roll and the tooth root of the other roll.

FIG. 2 shows in diagrammatic form one practical mechanism to drive the rolls 10, 11 whilst generating a substantially sinusoidal oscillation of the roll 11 relative to the roll 10. The rolls 10, 11 are interconnected by meshing equal-ratio spur gears 21, 22 connected to the rolls 10, 11 by shafts 23, 24, 25, 26, 27, 28 and universal joints 29, 30, 31, 32. The universal joints are arranged to transmit constant angular velocity from the shaft 28 to the shaft 24, and from the shaft 27 to the shaft 23. Shafts 23, 24, and 28 are mounted in bearings (not shown) in fixed structure. The shaft 27 is carried in bearings in a frame-work which includes plates 33, 34 jointed by a bar 35. The plates 33, 34 are pivoted about the axis of the shaft 28. A shaft 36 co-axial with shaft 28 and mounted in fixed bearings connects gear 21, through step-up gears 37, 38, 39, 40, to an eccentric 41. The gears 38, 39 and 40 are carried on rotatable shafts 42, 43 mounted in fixed bearings. The assembly is conveniently driven by an electric motor connected to one of the shafts 24, 36, 42 or 43.

On rotation of the roll 10, the train of gears causes the eccentric 41 to rotate, which in turn causes a connecting rod 44, in which the eccentric 41 is mounted, to oscillate. The connecting rod 44 is also provided to the bar 35 so that rotation of the eccentric 41 rocks the plates 33, 34 in substantially sinusoidal manner about the axis of the shaft 28. This in turn causes the gear 22 to roll back and forth around the gear 21, so that the gear 22 has a corresponding substantially sinusoidal torsional oscillation superimposed on its steady speed. By virtue of the torsional rigidity of the shafts 23, 25 and 27 and the universal joints 29, 31, a corresponding angular velocity pattern is transmitted to the roll 11.

Where a simple eccentric 41 is used, the step-up ratio from the shaft 36 to the shaft 43 must equal the number of teeth on each roll 10, 11. Alternatively, instead of the eccentric 41 there could be provided a cam having one or more lobes, and arranged on rotation to oscillate the plates 33, 34. By using a suitable cam it is possible to superimpose a non-sinusoidal torsional oscillation onto the steady rotational speed of the roll 11.

FIG. 3 shows an alternative arrangement to that of FIG. 2 in which the die rolls 10, 11 are driven by gearwheels 45, 46 mounted coaxially on the respective shafts of die-rolls 10, 11. The gear-wheels 45, 46 are driven by respective worm-wheels 47, 48 mounted on shafts 49, 50, which rotate in bearings (not shown). The shafts 49, 50 are connected to equal gear-wheels 51, 52 by shafts 53,54, Hookes joints 55, 56, 57, 58 and intermediate telescopic splined shafts 59, 60. Shafts 53, 54 are also carried in bearings (not shown). The gears 51, 52 are meshed with, and driven by, a further gear 61 connected to be driven by an electric motor 62.

The Hookes joints are arranged so that the forks on each of the intermediate shafts 59, 60 are in planes at a right angle to one another, in known manner so that the second-order substantially sinusoidal variations of angular velocity produced thereby are additive; In this way, when the shafts 53 and 54 are driven at constant angular speed, the shafts 49, 50 will be driven at the same speed but with a substantially sinusoidal torsional oscillation of twice per revolution superimposed thereon. The driven ratio between the worm-wheels 47, 48 and their respective gears 45, 46 is equal to half the number of teeth on the die rolls 10, 11. The magnitude of thesinusoidal variation in speed is adjusted by moving the assembly comprising the electric motor 62 and the set of gears 51, 52, 61 towards or away from the rolls 10, 11, as provided for by the splines in the shafts 59, 60 thereby changing the angles of the I-Iooke7s joints 55, 56, 57, 58. Where gears 51, 52 rotate in the same direction, it is necessary for the worm-wheels 47, 48 to be of opposite hand. The Hookes joints are so angularly disposed on their shafts as shown, that as one die roll 10 is accelerated, the other 11 is retarded. Clearly the axes l2, 13 may be parallel to shafts 49, 50, in which case gears 47, 48 are conveniently spur gears.

Referring now to FIGS. 4 to 6, FIGS. 4 and 5 show teeth having the same general form as that of the teeth of FIG. 1, but in this case the teeth have louvre-cutting means 65 formed on the flanks 20 of the teeth 14. The louvre-cutting means 65 are each formed as inserts in the teeth and comprise projections 66 extending away from the flank surfaces and obliquely so as to form corresponding slits and depressions (louvres) in the foil strip, in known manner.

The die rolls 10, 11 are made up of relatively thin discs, as indicated in FIG. 5, which are assembled to form alaminated roll 67, FIG. 6, the individual laminae being held together between end plates 68 by bolts 19 extending therethrough. Such an assembled roll, as shown in FIG. 6, is arranged so that the desired arrangement of louvres in the strip is obtained, in this case groups each consisting of three or six sets of louvres being spaced apart axially from one another.

Referring now to FIG. 7, an alternative die roll tooth form is shown. In this case the teeth 14 are each of sawtooth form, the tips 18 and roots 19 each consisting of points, the surfaces of the teeth consisting substantially wholly of the flanks 20 on which are formed louvrecutting means 65 as previously described with reference to FlGS. 4 to 6. Such teeth 14 will, when meshing with similarly-shaped teeth, produce corrugations of corresponding saw-tooth form. Oscillation of die rolls formed with such saw teeth is similar in principle to that already described with reference to the alternative tooth form except that ideally the relative angular velocity of the die rolls will be maintained at its maximum only for the instant when a tip is in engagement with a root. For producing such oscillations, oscillating means such as described with reference to FIGS. 2 and 3 may be employed arranged to produce a substantially sinusoidal oscillation suited to this tooth form.

It will be appreciated that the invention is particularly suited to producing corrugations have sharp changes in direction, at high rates. It is envisaged that the die rolls of the invention can operate satisfactorily producing such corrugated foil strip at the rate of at least 55 inches per second.

It is clearly not essential for the die rolls to have equal numbers of teeth, provided appropriate adjustment is made to the ratio of the driving gears. Similarly the teeth may have flat tips 18 or roots 19, or curved flanks 20. In FIG. 2, the plates 33, 34 need not be oscillated about the axis of the shaft 28 but could be oscillated about another axis parallel thereto, although generally this will be less convenient.

What we claim as our invention and desire to secure by Letters Patent of the United States is:

l. A corrugation-forming machine including two rotatable die rolls formed with intermeshing teeth between which the material to be corrugated is passed, drive means for rotating said die rolls, and oscillating means arranged to cause the relative angular velocity of said die rolls to change during their rotation so that the angular velocity of one die roll is less than or greater than its mean angular velocity when the radius, of the point of its teeth instantaneously in engagement with the teeth of the other roll is greater or less respectively than the pitch circle radius of said one die roll, the drive means including drive shafts to each of the die rolls, and the oscillating means being arranged to oscillate each of the drive shafts about their respective axes of rotation in opposite phase.

2. A machine according to claim 1 wherein the oscillating means is arranged to increase the angular velocity of one roll relative to the other where a tooth root of said one roll is engaged with a tip of said other roll and to decrease the angular velocity of said one roll relative to the other when a tip of said one roll is engaged with a root of said other roll.

3. A machine as claimed in claim 1 wherein the teeth of said die rolls are truncated, having convex tips, and having sharp corners between flanks of the teeth and the tips.

4. A machine as claimed in claim 1, wherein the teeth have convex root portions, and sharp comers between flanks of the teeth and the root portions.

5. A machine as claimed in claim 1, wherein flanks of the teeth are provided with louvre-forming surfaces.

6. A machine as claimed in claim 1, wherein flanks of the teeth are formed as arcs of circles.

7. A machine as claimed in claim 1, wherein the tips and the roots of the teeth are formed as arcs of circles,

whose centre is the axis of rotation of the corresponding die roll.

8. A corrugation-forming machine including two rotatable die rolls formed with intermeshing teeth between which the material to be corrugated is passed. drive means for rotating said die rolls, and oscillating means arranged to cause the relative angular velocity of said die rolls to change during their rotation so that the angular velocity of one die roll is less than or greater than its mean angular velocity when the radius of the point of its teeth instantaneously in engagement with the teeth of the other roll is greater or less respectively than the pitch circle radius of said one die roll,

the die rolls being mounted in bearings to rotate about I fixed axes of rotation, both die rolls being connected through shaft means to meshing gears, at least one of said die rolls being connected to the corresponding meshing gear through universal joints, a first of said meshing gears being mounted to rotate about a fixed axis, and means to cause the second said meshing gear to roll back and forth around part of said meshing gear when said die rolls are driven.

9. A machine as claimed in claim 8, wherein said second meshing gear is mounted on a shaft carried in a framework which is adapted to pivot about the axis of rotation of said first meshing gear, and there is provided an eccentric driven at a speed equal to the product of the rotational speed of the first meshing gear and the number of teeth on one of the die rolls, and a connecting rod in which the eccentric is mounted and which is connected to said framework to cause it to oscillate as the eccentric rotates.

10. A corrugation-forming machine including two rotatable die rolls formed with intermeshing teeth between which the material to be corrugated is passed, drive means for rotating said die rolls, and oscillating means arranged to cause the relative angular velocity of said die rolls to change during their rotation so that the angular velocity of one die roll is less than or greater than its mean angular velocity when the radius of the point of its teeth instantaneously in engagement with the teeth of the other roll is greater or less respectively than the pitch circle radius of said die roll, the drive means including a pair of shafts driven at constant angular velocity said shafts being connected to the respective die rolls, and the drive from at least one of the shafts to the corresponding die roll including a pair of Hookes joints so arranged as to produce sinusoidal variations in the angular velocity of the die roll driven thereby. v

11. A machine as claimed in claim 10, wherein each of said die rolls is driven from a constant angular velocity shaft through a pair of Hookes joints, whereby the angular velocity of both die rolls is caused to oscillate.

can be adjusted. 

1. A corrugation-forming machine including two rotatable die rolls formed with intermeshing teeth between which the material to be corrugated is passed, drive means for rotating said die rolls, and oscillating means arranged to cause the relative angular velocity of said die rolls to change during their rotation so that the angular velocity of one die roll is less than or greater than its mean angular velocity when the radius of the point of its teeth instantaneously in engagement with the teeth of the other roll is greater or less respectively than the pitch circle radius of said one die roll, the drive means including drive shafts to each of the die rolls, and the oscillating means being arranged to oscillate each of the drive shafts about their respective axes of rotation in opposite phase.
 2. A machine according to claim 1 wherein the oscillating means is arranged to increase the angular velocity of one roll relative to the other where a tooth root of said one roll is engaged with a tip of said other roll and to decrease the angular velocity of said one roll relative to the other when a tip of said one roll is engaged with a root of said other roll.
 3. A machine as claimed in claim 1 wherein the teeth of said die rolls are truncated, having convex tips, and having sharp corners between flanks of the teeth and the tips.
 4. A machine as claimed in claim 1, wherein the teeth have convex root portions, and sharp corners between flanks of the teeth and the root portions.
 5. A machine as claimed in claim 1, wherein flanks of the teeth are provided with louvre-forming surfaces.
 6. A machine as claimed in claim 1, wherein flanks of the teeth are formed as arcs of circles.
 7. A machine as claimed in claim 1, wherein the tips and the roots of the teeth are formed as arcs of circles, whose centre is the axis of rotation of the corresponding die roll.
 8. A corrugation-forming machine including two rotatable die rolls formed with intermeshing teeth between which the material to be corrugated is passed. drive means for rotating said die rolls, and oscillating means arranged to cause the relative angular velocity of said die rolls to change during their rotation so that the angular velocity of one die roll is less than or greater than its mean angular velocity when the radius of the point of its teeth instantaneously in engagement with the teeth of the other roll is greater or less respectively than the pitch circle radius of said one die roll, the die rolls being mounted in bearings to rotate about fixed axes of rotation, both die rolls being connected through shaft means to meshing gears, at least one of said die rolls being connected to the corresponding meshing gear through universal joints, a first of said meshing gears being mounted to rotate about a fixed axis, and means to cause the second said meshing gear to roll back and forth around part of said meshing gear when said die rolls are driven.
 9. A machine as claimed in claim 8, wherein said second meshing gear is mounted on a shaft carried in a framework which is adapted to pivot about the axis of rotation of said first meshing gear, and there is provided an eccentric driven at a speed equal to the product of the rotational speed of the first meshing gear and the number of teeth on one of the die rolls, and a connecting rod in which the eccentric is mounted and which is connected to said framework to cause it to oscillate as the eccentric rotates.
 10. A corrugation-forming machine including two rotatable die rolls formed with Intermeshing teeth between which the material to be corrugated is passed, drive means for rotating said die rolls, and oscillating means arranged to cause the relative angular velocity of said die rolls to change during their rotation so that the angular velocity of one die roll is less than or greater than its mean angular velocity when the radius of the point of its teeth instantaneously in engagement with the teeth of the other roll is greater or less respectively than the pitch circle radius of said die roll, the drive means including a pair of shafts driven at constant angular velocity said shafts being connected to the respective die rolls, and the drive from at least one of the shafts to the corresponding die roll including a pair of Hooke''s joints so arranged as to produce sinusoidal variations in the angular velocity of the die roll driven thereby.
 11. A machine as claimed in claim 10, wherein each of said die rolls is driven from a constant angular velocity shaft through a pair of Hooke''s joints, whereby the angular velocity of both die rolls is caused to oscillate.
 12. A machine as claimed in claim 10, wherein each die roll is driven through a worm and worm-wheel, the gear ratio of which is equal to half the number of teeth on the respective die roll.
 13. A machine as claimed in claim 10, wherein the Hooke''s joints are interconnected by an extensible transmission shaft, whereby the amplitude of the variation in angular velocity of the die roll driven thereby can be adjusted. 